Teres Major Muscle

Origin

The teres major muscle originates from the posterior aspect of the inferior angle of the scapula and its adjacent area.

Insertion

The fibers of the teres major muscle travel superolaterally and insert, via a flat tendon, onto the crest of the lesser tubercle of the humerus. This insertion site is located medial to the insertion site of the latissimus dorsi muscle.

Key Features & Anatomical Relations

The teres major muscle is found in the shoulder region. It is a thick, fusiform type of skeletal muscle. It is located:

- anterior (deep) to the long head of triceps brachii muscle;

- posterior (superficial) to the scapula, coracobrachialis muscle;

- superior to the latissimus dorsi muscle;

- inferior to the teres minor and infraspinatus muscles.

The teres major muscle contributes to the formation of the posterior wall of the axilla, and its inferior margin contributes to the formation of the posterior axillary fold.

Actions & Testing

The teres major muscle is involved in multiple actions:

- adducts the arm at the glenohumeral (shoulder) joint;

- medially rotates the arm at the glenohumeral joint;

- assists in extension of the arm at the glenohumeral joint;

- helps stabilize the glenohumeral joint.

The teres major muscle can be tested by adducting the arm at the glenohumeral joint against resistance, during which the muscle can be seen and palpated (Sinnatamby, 2011).

List of Clinical Correlates

- Injury or rupture of rotator cuff

References

Sinnatamby, C. S. (2011) Last's Anatomy: Regional and Applied. ClinicalKey 2012: Churchill Livingstone/Elsevier.